The contractual agreement is part of the developer's push into mobile games, having made its name with browser-based strategy titles such as Forge of Empires.

InnoGames plans to use Unreal Engine 4 to power a role-playing game for iOS and Android, due for release in 2016. The project currently has 25 people working on it.

"The mobile games market is heavily fought over and the competitive landscape leads to a number of high quality products," said InnoGames' head of producing Dennis Rohlfing. "This trend will not cease in the near future, which is why our goal is to adhere to the standards of the mobile market.

"The Unreal Engine is a great technological foundation, especially for the development of prototypes. This way, we can focus on gameplay and optimized usability right from the beginning. Also, using a solid engine allows us to focus on platform agnostic development for iOS and Android equally."